In recent years, wireless communication advances rapidly. There are many wireless products developed under many wireless standards. Those standards include cellular standards such as GSM (Global System for Mobile), IS-95 (Interim Standard 95)/CDMA2000 (Code Division Multiple Access 2000), 3GPP/UMTS/LTE, WiMax/IEEE 802.16e and local area networks standards such as WiFi/IEEE 802.11, BlueTooth, Zigbee, and UWB/IEEE 802.15 etc.
In terms of the bi-directional wireless communication, wireless system can also be simply categorized as FDD (frequency division duplex) and TDD (time division duplex). Two way communications use two different frequencies in FDD system and use the same frequency but different time slots in TDD system.
In general, a wireless communication system has four major subsystems, i.e. antenna system, radio system, base-band processing subsystem and MAC processor. Their responsibilities are:
Antenna is responsible to pick a signal or to radiate a signal;
Radio system will select and regulate the interested signal coming down from an antenna or regulate the signal from base-band subsystem before it goes to the air;
Base-band processing subsystem is the place the messages get processed such as encoding/decoding, modulation/demodulation, encryption/decryption, filtering etc.;
MAC (media access control) will re-format the messages properly either suitable for transmission or suitable for reception.
Apparently, antenna system is a critical element and determines the signal quality in the first place.
Most of the mobile wireless terminals today installed an omni-directional antenna with the pre-determined performance.
Omni directional means the antenna transmits and receives from all the directions except along the antenna line. On the other hand, most cellular networks deployed today have 3 sectors topology with directional antennas usually mounted on a cellular tower. Omni antennas not only cause significant interferences to neighbor users, but also cause signal energy diverse therefore waste terminal battery.
Pre-determined performance means that the user can hardly do anything on antenna performance.
So there is a need to implement directional antenna in mobile wireless terminal side to minimize the interferences and to align with cellular network topology so that the uplink (terminal transmits and base station receives) link budget can be balanced with that of downlink (base station transmits and terminal receives). However, to implement directional antennas is difficult both in technology implementation and in cost effectiveness. When a directional antenna is implemented, it must guarantee those system information such as broadcast information, paging information etc (can arrive from any direction) still can be heard. It also needs to guarantee the existing terminal architecture and form factor a minimum change.
One embodiment of this invention is to disclose directional antennas systems and apparatus for wireless terminals and handhelds.
Another embodiment of the invention is to provide directional transmission antenna selection schemes basing on a simple compass reading.
The foregoing embodiments of the invention are illustrative that can be implemented by the various exemplary embodiments and the corresponding descriptions. It will be appreciated by those skilled in the art that these and other embodiments can be modified for other wireless devices antennas configurations.